In the May 8, 1995, issue of the Archives, Kelliher and Alexis1 inquired about the relative effectiveness of the intravenous and subcutaneous routes of phytonadione administration for the reversal of warfarin overanticoagulation.2,3

Both intravenous and subcutaneous routes of phytonadione administration are effective. However, there is a small risk of an anaphylactic reaction with the intravenous preparation. Vitamin K is absorbed rapidly by the subcutaneous route. Therefore, the subcutaneous route is preferable unless problems are anticipated with subcutaneous absorption, such as might occur in patients with severe peripheral circulatory failure.